Record sheet holder



2 Sheets-Sheet 1 F. L. PREscoTT RECORD SHEET HOLDER @riginal Filed sept.5, 1931 July 5, 1938.

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F. L. PRIESCOTT RECORD SHEET HOLDER lOriginal` Filed Sept` 5, 1931 2s'neetsrsheet m tu( Trag/Veys Patented July 5, 1938 UNITED STATES PATENTorrics 561,488. Divided and this application October 15, 1936, SerialNo. 105,777

5 Claims.

(Granted under the act of March 3, 1883, as

amended April 30,

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to subject matter which has been divided out ofmy co-pending application, Serial No. 561,488, filed September 5, 1931,for a Torsional vibration recording instrument, which matured intoPatent No. 2,069,271, dated February 2, 1937. l

The prior led application discloses a torsiometer designed for the studyand the recordation of the vibration characteristics of engine crankshafts, particularly aircraft engine crank shafts, and is directed moreor less to the vibration exhibiting mechanism of the instrument whereasthe instant case is directed to novel recording features comprisingchart and drum handling shown and described but not claimed in theparent application above identied.

ln the accompanying drawings illustrating the invention:-

irigure 1 is a side View, partly in elevation and partly in section ofthe torsiometer instrument and record-receiving member in assembledrelation;

Figure 2 is an end view of the torsiometer with the record receivingmember omitted and with fragments broken away to expose the elasticdrive;

Figure 3 is a top view of the record-holder or drum with therecord-receiving card omitted;

Figure l is a side view of the assembled torsicmeter andrecord-receiving member, the reverse of that shown in Figure 1 and withthe parts in elevation;

Figure 5 is a cross sectional view on an enlarged scale of the recordsheet holder or drum taken on line 5 5 of Figure 4 and showing therecord sheet clamping mechanism in released position;

Figure 5 is a view similar to Figure 5 but showing the record sheetclamping mechanism` in sheet-clamping position, and

Figure 7 is a view in perspective of a portion of the torsiometer andrecording mechanism with the record sheet and sheet-clamping mechanismand the index in a disassembled state.

The vibration exhibiting mechanism for which the herein described recordsheet holder is especially adapted and to which the claims of the prior.filed parent application are directed shown generally in Figures 1, 2and 3 and, brieiiy described, comprises a non-uniformly rotatable memberI and a uniformly rotatable member 2 with mechanism for impartingvibratory motion to an indicating hand 3 carrying a stylus or pencil fi.The member l comprises a short shaft or arbor having an expanding spline5 at one end for attachment to a starter claw E of an engine crank shaftwhereby the arbor will be r0- tated at the same non-uniform angularvelocity as and with the same torsional vibration characteristics of thecrank shaft. The member 2 is an inertia fiywheel supported on the arborand having an elastic or spring drive connection Z therewith whereby itis caused to rotate with the crank shaft and arbor but at asubstantially uniform or constant angular velocity equal to the averageangular velocity of the crank shaft; any torsional vibrations in thearbor resulting from the non-uniform angular velocity of the crank shaftbeing substantially absorbed by the elastic drive connection and, hence,not appreciably affecting or disturbing the uniform rotation of theflywheel. Mounted in a bearing bracket 8 fixed to the fly wheel cover i)so as to turn therewith is a rotatable and axially slidable shaft i@carrying the indicating hand 3. Shaft i@ and indicating hand 3 areoperatively connected to the arbor, to have an oscillatory orvibrational movement imparted thereto in response to variations in theangular velocity of the crank shaft, by a flexibie cable l l connectedat its ends to a driving member' l?. fixed on the arbor l and windingaround a cable drum i3 fixed on the indicator shaft lll. The resultantdisplacement of the pencil-bearing end of the indicating hand gives anamplified indication of the torsional deflection or vibration of thecrank shaft and a record of the displacement is made on an ordinaryindicator paper or card til lmounted on a support or holder l5. Sincethe pencil revolves with the instrument, the holder with record paper inplace thereon is held in the hand, placed over a rotatpilot or centeringguide l@ at the end of the arbor, and then quickly pushed in andwithdrawn. During the last one thirty-second inch of motion inwardlyupon the guide, the holder i5 operates a bell-crank system il whichpresses yf' the pencil against the paper. The pencil in its travel`around the record-sheet holder will trace on the record-receiving sheetor cord a wavy line or curve, the undulations of which constitute arecord or chart of the torsional vibrations of the engine crank shaft.The record of one engine cycle, or two revolutions of the crank shaft,comprises two curves superposed.

The instant invention diiers from conventional and prior torsiometers inthat records produced by the former are made on paper rolls orcylindrical strip which are subsequently unrolled and attened out -withthe straightened record strips arranged in relatively overlappingrelation for better comparison of the different records whereas therecords produced by the latter are generally in the form of polardiagrams on the faces of flat circular cards or disks. Hence, for thepurposes of the present invention, the record sheet holder I5 is made inthe form of a cylinder or drum having a pilot-receiving axial bore I8opening inwardly of one end and a hollow handle 9 extending axially fromits opposite end. The drum I5, with the record-receiving strip I4clamped thereon as hereinafter explained, is adapted to be placedendwise upon the pilot bearing I5 of the torsiometer and slid inwardlythereon by means of its handle I9 to a position predetermined by thesetting of an adjustable stop block the drum being held manually againstrotation with the pilot bearing turning within the bore I8. The pilotbearing thus serves as a guide for centering the drum properly withrespect to the axis of rotation of the revolving hand and pencil.

For the purpose of clamping the record-receiving strip to the drum sothat there will be no slack, a sheet clamping mechanism is provided onthe record sheet holder in the following manner. The drum I5 is providedwith a longitudinally extending cylindrical bore 2| of substantiallysmall diameter adjacent to but below the outer surface of the drum andopening outwardly of the opposite ends of the latter. The portion of thedrum intermediate the bore 2| and the diametrically adjacent surface iscut away to provide an open narrow slot 22 coextensive with the bore 2|.A cylindrical rod 23 having a paperreceiving slot 24 is journaled insaid bore 2| to be turned about an axis in either direction for movingthe paper-receiving Slot to and from a position in which it is alignedwith the drum slot 2|); the rod being manually turned by means of ahandle 25 carried by a head 26 on the outer end of the rod. Head 26 isformed as a prismoidal body having angularly disposed fiat lateral facesa-b-c and the drum handle I9 has a plunger 21 mounted therein with asquare head 28 operating through a square opening 29 in the handle toengage each of the said flat faces for the full width of the latter asthey are brought into alignment with the plunger head 28 by the turningof the rod 23; the head 28 of the plunger being pressed against the sideof the body 26 by the thrust of a plunger-encircling spring 30. As Willbe obvious from the construction illustrated in Figures 5 and 6, theengagement of the plunger with the body 25 does not restrict the turningof the rod 23 manually to one direction and whether the rod be turnedmanually about its axis in a clockwise or counterclockwise direction,the top fiat face of the plunger head is adapted to contact the lateralfaces of the body 26 successively and in a plane normal to a lineperpendicular to the axis of the body and passing centrally through thecontacting faces. When the flat face a of the rod is in abutment withthe head of the plunger, as illustrated in Figure 5, the handle 25 isupright and the slot 24 of the rod is in alignment with the slot 22 ofthe drum. In this position of the parts, the holder is in conditioneither to have a record-receiving sheet attached thereto or to release apreviously placed record-receiving sheet. In attaching the sheet, thelatter is placed around the outside of the drum with its free endsdisposed inwardly through the drum slot 22 and secured in the slot 24 ofthe rotatable rod 23. The handle 25 is then moved from the uprightposition shown in Figure 5 to the inclined position shown in Figure 6,imparting to the rod a turning movement that shifts the slot 24 in adirection clockwise of the slot 22 and thereby drawing the ends of thesheet or strip into the drum and tightening the sheet about thesupporting surface of the drum. In T same angular position on the pilotbearing when making .a number of records with a particular setting ofthe engine and for identifying this position a manually settable indexis provided, This index consists of a rotatable ring 3| encircling thedrum handle i9 and a pointer 32 having a screw-threaded stud or shank 33engaged in a screw threaded opening 34 in the ring and of a length tobear against the drum handle; the pointer having a knurled head orthumb-piece 35 whereby it may be turned either i to screw the stud tightagainst the drum handle for locking the ring against rotation or tounscrew the stud to permit relative rotation of the ring and drum. Insetting the index, the drum with record receiving sheet in place thereonis slid over the pilot bearing and, with the engine set on top center ofone cylinder, the beginning of the card is lined up with the pencil byturning the drum relatively to the ring until the slot 22 is oppositethe pencil, the pointer being meanwhile held in some selected referenceposition, such as the vertical, which it is intended to occupy wheneverthe drum is placed on the pilot bearing. The pointer is then screweddown tight so that its angular distance from the beginning of the cardis xed. This serves to locate the crank positions on the record and itwill be obvious that if the drum., subsequent to its withdrawal from thepilot bearing at any stage in the operation of the engine, be replacedupon the pilot bearing with the pointer in vertical upright position, itwill assume its proper or original relationship with` respect to 'thecycle of the engine.

In the absence of any torsional vibration in the crank shaft, the pointof the stylus or pencil would travel around the drum without deviationfrom its circular path and would trace a straight line on the recordsheet I4. However, in the actual operation of the engine, the stylus hasa vibrational movement due to torsional vibrations set up in the crankshaft and resulting in the relative movement of the driving and drivenmembers with which the stylus is operatively connected. Under suchconditions, the point of the stylus in its travel around the drum willtrace on the record-receiving sheet a wavy line or curve, theundulations of which constitute a record of the torsional vibrations ofthe engine crank shaft.

Having thus described the invention, what is claimed is:

1. A record sheet holder having a, record receiving surface adapted tobe placed in contact with a marking device to be marked thereby with arecord of any relative displacement of the holder and the markingdevice, and a manually settable index on said holder for orientation toa selected position with respect to the initial setting of the holderand marking device whereby when the said holder is withdrawn fromContact at any stage of relative displacement of holder and markingdevice and again placed in contact with the marking device with theindex in the said selected position it will be properly positioned withrespect to the marking device to obtain a corresponding relationship ofthe record and the relative movements of the holder and the markingdevice.

2. The combination such as defined in claim l, in which the record sheetholder is provided with a cylindrical handle and the index consists of aring provided with a pointer and rotatable about the said handle forvarying the position of the pointer.

3. The combination such as dened in claim 1, in which the record sheetholder comprises a drum having a cylindrical handle and the manuallysettable index consists of a ring rotatable about said handle andprovided with a screw threaded radial opening and a pointer providedwith a screw threaded shank engaged in the said radial opening of thering and having a knurled head whereby it may be turned to screw thesaid shank down tight against the said handle to lock the ring againstrotation or to unscrew the shank to free the ring for adjustment aboutthe handle to change the angular position of the pointer.

4. A sheet supporting and tautening device comprising a drum aroundwhich the sheet is adapted to be placed, a roller journaled in said drumand adapted to receive the ends of the sheet, means for turning theroller about its axis in either direction to tauten the sheet around thedrum, a prismoidal body connected with the roller to be turnedtherewith, a spring-pressed element mounted on the drum and having aflat face frictionally and yieldingly bearing against the side of thebody for contacting the lateral faces of the latter successively and forthe full width of each during the turning of the said roller in eitherdirection whereby to arrest the turning motion of the same.

5. A sheet supporting and tautening device having, in combination, adrum, a handle extending axially from one end of the drum and being ofless diameter than the drum, a ring releasably fixed on the handle inslightly spaced relation to the end of the drum, a rod journaledlengthwise of the drum to be turned about the axis in either directionsubjacent the periphery of the latter and provi-ded at the handle end ofthe drum with a coaxial prismoidal head disposed in the space betweenthe said ring and the adjacent end of the drum, means carried by thehead whereby it may be turned manually, and a spring pressed plungermounted in the said handle and frictionally and yieldably bearingagainst the side of the prismoidal head, said plunger having a flat faceadapted when the roller is turned about its axis in either direction tocontact the lateral faces of the said head successively and in a planenormal to a line perpendicular to the axis of the head and passingcentrally through the contacting faces.

FORD L. PRESCO'I'I.

